Resin supplying method, resin supplying device, and method for manufacturing press-molded thermoplastic resin products

Abstract

To supply a mold with a molten resin composition with high viscosity with good quantitativeness.SOLUTION: A resin supply method according to the present invention has: melting step (101) for generating a molten resin composition; transfer step (102) for transferring the molten resin composition to a discharge part; discharge step (103) for supplying the molten resin composition to a mold from the discharge part ; and heating and cutting step (104) for non-contactly and instantaneously heating and cutting the molten resin composition discharged to the mold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin supplying method, a resin supplying device, and a method for manufacturing a press-molded product of a thermoplastic resin. [Background technology]

[0002] A press molding method is known in which a thermoplastic resin is heated using an extruder or the like to prepare a molten resin composition, and the molten resin composition is discharged from a discharge port of a resin supplying device and quantitatively supplied to a mold, followed by press molding to manufacture a product. Typically, molten resin compositions are viscous. Therefore, in the press molding method, when a fixed amount of the molten resin composition is supplied to a mold, stringiness of the molten resin composition occurs between the discharge port and the mold. Furthermore, the weight of the stringy molten resin composition residue between the discharge port and the mold varies with each resin supply, resulting in a problem of loss of quantitative supply of the molten resin composition to the mold.

[0003] To address the above-mentioned problems, for example, Patent Document 1 discloses a technique for cutting the stringy portion of the molten resin composition between the discharge port and the mold with a cutter in a press molding method for a molten resin composition of a general-purpose resin such as a polyethylene-based resin or a polyolefin-based resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-078481 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the conventional technology described in Patent Document 1 does not adequately cut the stringy portions of molten resin compositions of thermoplastic resins (e.g., poly(3-hydroxyalkanoate)-based resins (hereinafter sometimes referred to as "P3HA-based resins")), which are more viscous than the above-mentioned general-purpose resins, and there is room for improvement in terms of quantitatively supplying the molten resin composition to a mold.

[0006] One aspect of the present invention aims to provide a resin supply method and resin supply device that can cut the stringy portion between the discharge port and the mold and supply a molten resin composition of a thermoplastic resin with relatively high viscosity to the mold with high quantitative accuracy, as well as a method for manufacturing press-molded products of thermoplastic resin. [Means for solving the problem]

[0007] In order to solve the above problems, a resin supplying method according to one embodiment of the present invention includes a melting step of melting a resin composition containing a thermoplastic resin to produce a molten resin composition, a transfer step of transferring the molten resin composition to a discharge section, a discharge step of supplying the molten resin composition from the discharge section to a mold, and a heating and cutting step of contactlessly and instantaneously heating and cutting the molten resin composition discharged from the discharge section to the mold.

[0008] In addition, in order to solve the above-mentioned problems, a resin supplying device according to one embodiment of the present invention includes a melting section that melts a resin composition containing a thermoplastic resin to produce a molten resin composition, a discharge section that supplies the molten resin composition to a mold, a transfer section that transfers the molten resin composition from the melting section to the discharge section, and a heating and cutting section that heats and cuts the molten resin composition discharged from the discharge section to the mold in a non-contact and instantaneous manner. [Effects of the Invention]

[0009] According to one aspect of the present invention, a molten resin composition of a thermoplastic resin having a relatively high viscosity can be supplied to a mold with good quantitative accuracy by cutting the stringy portion between the discharge portion and the mold. [Brief explanation of the drawings]

[0010] [Figure 1] 3A to 3C are diagrams for explaining various steps of a resin supplying method according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing a schematic configuration of a resin supplying device according to an embodiment of the present invention; [Figure 3] 301 and 302 are diagrams for explaining the lifting mechanism of the discharge unit in the resin supplying device shown in FIG. [Figure 4] 3 is a diagram showing a configuration of a modified example of the heating and cutting unit provided in the resin supplying device shown in FIG. 2. FIG. [Figure 5] 501 is a cross-sectional view showing a schematic configuration example of the nozzle part of the discharge part shown in FIG. 2, and 502 is a cross-sectional view showing a schematic configuration of a zero cavity nozzle as a modified example of the nozzle part shown in 501. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will be described in detail below. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more and B or less." In addition, all documents described in this specification are incorporated herein by reference.

[0012] [Outline of one embodiment of the present invention] As described above, in conventional press molding, a technique has been known in which a cutter is used to cut the stringy portion of the molten resin composition between the discharge port and the mold in order to supply a fixed amount of the molten resin composition to the mold. However, the present inventors have found that when a molten resin composition of a thermoplastic resin with relatively high viscosity (e.g., a P3HA-based resin) is used, this technique can result in (a) the molten resin composition adhering to the cutter or (b) new stringing occurring between the cutter and the mold. As a result, it has been found that the above technique has the problem of making it difficult to supply a fixed amount of the molten resin composition to the mold. In particular, the present inventors' investigations have revealed that cutting the stringy portion is difficult even when using a cutter coated with Teflon (registered trademark) to prevent adhesion of the molten resin composition.

[0013] As a result of intensive research conducted by the inventors to solve the above problems, they discovered that when supplying a molten resin composition having a relatively high viscosity to a mold, the molten resin composition can be supplied to the mold with a good quantitative rate by heating and cutting the molten resin composition between the nozzle portion and the mold without contacting it.

[0014] The resin supply method according to this embodiment (hereinafter sometimes referred to as the present resin supply method) comprises a melting step of melting a resin composition containing a thermoplastic resin to produce a molten resin composition, a transfer step of transferring the molten resin composition to a discharge section, a discharge step of supplying the molten resin composition from the discharge section to a mold, and a heating and cutting step of contactlessly and instantaneously heating and cutting the molten resin composition discharged from the discharge section to the mold.

[0015] Furthermore, the resin supply device according to this embodiment (hereinafter sometimes referred to as this resin supply device) is configured to include a melting section that melts a resin composition containing a thermoplastic resin to produce a molten resin composition, a discharge section that supplies the molten resin composition to a mold, a transfer section that transfers the molten resin composition from the melting section to the discharge section, and a heating and cutting section that heats and cuts the molten resin composition discharged from the discharge section to the mold in a non-contact and instantaneous manner.

[0016] According to the resin supplying method and the resin supplying device, the molten resin composition discharged from the discharge portion into the mold is heated and cut instantaneously without contact, so that when a relatively viscous molten resin composition is supplied to the mold, cutting the stringy portion between the nozzle portion and the mold does not create a new stringy portion, and the molten resin composition can be supplied to the mold with a high quantitative accuracy.

[0017] Furthermore, according to this resin supply method and this resin supply device, by using a biodegradable resin in the ocean (for example, P3HA-based resin, etc.), it is possible to suppress marine pollution due to waste, thereby contributing to the achievement of Sustainable Development Goals (SDGs) such as Goal 12 "Ensure sustainable consumption and production patterns" and Goal 14 "Conserve and sustainably use the oceans and marine resources for sustainable development." The resin supply method and this resin supply device are described in further detail below.

[0018] (Resin supply method) 1 is a diagram illustrating various steps of a resin supplying method according to one embodiment of the present invention. As shown in FIG. 1, the resin supplying method includes a melting step 101, a transferring step 102, a discharging step 103, and a heating and cutting step 104.

[0019] In the melting step 101, a resin composition containing a thermoplastic resin is melted to produce a molten resin composition. Any conventionally known method can be used to melt the resin composition as long as it can form a molten resin composition containing a thermoplastic resin. Preferably, the melting step includes a melt-kneading step of melt-kneading the resin composition containing a thermoplastic resin.

[0020] The mode of the melt-kneading step is not particularly limited as long as a melt-kneaded resin composition can be obtained. Specific examples of the melt-kneading step include the following methods (a1) and (a2): (a1) A method in which a resin composition containing a thermoplastic resin is prepared by mixing or blending using a mixer or the like, and then the resin composition is supplied to a melt-kneading device and melt-kneaded; (a2) A method in which raw materials for a resin composition containing a thermoplastic resin are supplied to a melt-kneading device, and a resin composition is prepared (completed) in the melt-kneading device, and the resin composition is melt-kneaded.

[0021] In the method (a1), the order in which the raw materials for the resin composition containing a thermoplastic resin are mixed or blended (dry blended) is not particularly limited.In the method (a2), the order in which the raw materials for the resin composition containing a thermoplastic resin are supplied to a melt-kneading device is not particularly limited.

[0022] In the method (a1), the mixing device is not particularly limited, and examples thereof include a ribbon blender, a flash blender, a tumbler mixer, and a super mixer.

[0023] In the methods (a1) and (a2), the melt-kneading device is not particularly limited and examples thereof include an extruder, a kneader, a Banbury mixer, a roll, etc. From the viewpoint of excellent productivity and convenience, the melt-kneading device is preferably an extruder, and more preferably a twin-screw extruder.

[0024] In the melt-kneading step, for example, when the thermoplastic resin is a P3HA-based resin, the temperature at which the resin composition is melt-kneaded cannot be generally specified because it depends on the physical properties (melting point, weight-average molecular weight, etc.) of the P3HA-based resin and the type of additive used. Regarding the temperature at which the resin composition is melt-kneaded, for example, the temperature of the molten resin composition discharged from the discharge port (hereinafter sometimes referred to as the composition temperature) is preferably 140°C to 190°C, more preferably 150°C to 180°C, and even more preferably 160°C to 170°C. If the composition temperature is 150°C or lower, unmelted P3HA-based resin may be generated. On the other hand, if the composition temperature is 180°C or higher, the P3HA-based resin may be thermally decomposed.

[0025] In the transfer step 102, the molten resin composition is transferred to a discharge section. The method for transferring the molten resin composition to the discharge section is not particularly limited, and any known transfer method can be used. Preferably, in the transfer step 102, the molten resin composition is transferred quantitatively to the discharge section. In this case, the transfer device may be any device capable of transferring the molten resin composition quantitatively, and examples thereof include a shot pump (note: a pump that is a constant volume pump like a syringe and repeatedly sucks and discharges), a manifold block, and a gear pump. Among these, it is preferable to use a gear pump as the transfer device. That is, in the transfer step 102, it is preferable to use a gear pump to transfer the molten resin composition to the discharge section. The gear pump is not particularly limited as long as it is capable of transferring the molten resin composition quantitatively to the discharge section, and any known device can be used.

[0026] Furthermore, in the transfer step 102, a transfer body may be provided between the transfer device and the discharge portion, and the molten resin composition may be transferred from the transfer device to the discharge portion via the transfer body. The transfer body is not particularly limited as long as it is configured to be able to transfer the molten resin composition. The transfer body is preferably a hot hose. The hot hose is configured to be able to transfer the molten resin composition having the above-mentioned composition temperature, and is composed of, for example, a heater, a heat-insulating layer, an inner tube, and the like. Among these, from the viewpoints of pressure resistance and heat resistance, it is preferable that the material of the inner tube of the hot hose is Teflon (registered trademark).

[0027] In the discharge step 103, the molten resin composition is supplied from the discharge part to the mold. The method for supplying the molten resin composition from the discharge part to the mold is not particularly limited. Preferably, from the viewpoint of mass productivity of press-molded articles, the discharge part is installed directly above the mold, and the molten resin composition is supplied to the mold by being discharged from the discharge part and dropped into the mold.

[0028] In the discharge step 103, the configuration of the discharge unit is not particularly limited as long as it is capable of discharging the molten resin composition, and any conventionally known configuration can be used. Examples of the configuration of the discharge unit include a configuration equipped with a gear pump and a configuration equipped with an automatic opening and closing nozzle. Specific examples of the discharge unit include a plunger type discharger, a pre-plunger type discharger, and a screw type discharger.

[0029] Furthermore, for molten resin compositions having relatively high viscosity, it is preferable to intermittently discharge the molten resin composition in the discharging step 103. This improves the quantitation of the molten resin composition supplied to the mold. In the discharging step 103, it is preferable that the discharging section includes a nozzle that intermittently discharges the molten resin composition. Such a nozzle section can be realized, for example, by a nozzle section equipped with an opening / closing mechanism that opens and closes the discharge port. The nozzle section intermittently discharges the molten resin composition by alternately opening and closing the discharge port using the opening / closing mechanism.

[0030] Furthermore, the intermittent discharge of the molten resin composition may be performed by alternately starting and stopping the discharge operation periodically, or may be performed non-periodically. When the discharge operation is alternately and periodically started and stopped, the period of start and stop of the discharge operation can be appropriately set depending on the composition temperature, the viscosity of the molten resin composition, etc.

[0031] For example, when the thermoplastic resin is a P3HA-based resin, the intermittent dispensing of the molten resin composition preferably stops the dispensing operation every 1 to 30 seconds, more preferably every 1 to 15 seconds. The stop time of the dispensing operation is preferably 1 to 15 seconds, more preferably 1 to 5 seconds. This has the advantage of preventing the properties of the P3HA-based resin from deteriorating due to heat in the molten resin composition.

[0032] Furthermore, from the viewpoint of improving the quantitative supply of the molten resin composition to the mold, it is preferable to supply the molten resin composition to the mold from a zero-cavity nozzle in the discharge step 103. By using a zero-cavity nozzle, it is possible to prevent stringing of the molten resin composition between the nozzle and the mold. The specific configuration of the zero-cavity nozzle will be described later.

[0033] In the heating and cutting process 104, the material is cut from the discharge section to the mold. Discharged The molten resin composition is cut by heating instantaneously without contacting the composition. In this way, when the molten resin composition is supplied to the mold, the molten resin composition between the nozzle portion and the mold is cut by heating instantaneously without contacting the composition, so that the molten resin composition can be supplied to the mold with good quantitative accuracy.

[0034] Here, "heating and cutting without contact" means heating and cutting the molten resin composition without contacting the heat source for heating with the molten resin composition. The distance between the heat source and the molten resin composition is not particularly limited as long as the molten resin composition can be instantaneously heated and cut. When the heat source is a hot air heater described below, the distance can be appropriately set depending on the performance of the hot air heater, the adhesiveness of the molten resin composition, and the like. When the heat source is a hot wire described below, the distance can be appropriately set depending on the temperature performance of the hot wire, the adhesiveness of the molten resin composition, and the like. Furthermore, "instantaneously heating and cutting" means cutting the molten resin composition simultaneously with heating by the heat source. Here, "simultaneously with heating by the heat source" means simultaneously within the measurement limit, and refers to within 3 seconds, preferably within 1 second, of heating by the heat source.

[0035] The present inventors have newly discovered that even if at least one of the zero-cavity nozzle and the gear pump is used for a molten resin composition of a relatively viscous thermoplastic resin such as a P3HA-based resin, stringing occurs between the nozzle and the mold, and this is insufficient to improve the ability to quantitatively supply the molten resin composition to the mold. In order to prevent stringing from occurring when using a molten resin composition of a relatively viscous thermoplastic resin, the heat cutting step 104 is essential.

[0036] The method for heating and cutting the molten resin composition in the heating and cutting step 104 is not particularly limited as long as it can heat and cut the molten resin composition instantaneously without contact. For example, radiant heat from a heat source may be used to heat and cut the molten resin composition instantaneously without contact. In this case, hot air may be used to heat and cut the molten resin composition instantaneously without contact. A hot air heater is preferably used as the heat source that supplies hot air to the molten resin composition. By adopting this heating and cutting method using hot air, new stringing due to the cut molten resin composition is less likely to occur. Therefore, the molten resin composition can be cut at the same location every time the dispensing operation is performed. As a result, the molten resin composition can be supplied quantitatively to the mold.

[0037] Alternatively, the molten resin composition may be instantaneously heated and cut without contact using a hot wire (heated metal wire) in the heat cutting step 104. In this case, the hot wire as a heat source is brought close to the molten resin composition without contact, and the molten resin composition is instantaneously heated and cut by radiant heat from the hot wire.

[0038] Furthermore, in the heat-cutting step 104, the molten resin composition is preferably instantaneously heated to a temperature equal to or higher than the softening temperature of the thermoplastic resin +50°C. The instantaneous heat-cutting temperature equal to or higher than the softening temperature of the thermoplastic resin +50°C can be appropriately set depending on the positional relationship between the heat-cutting unit used to perform the heat-cutting step and the molten resin composition. For example, when a hot air heater is used as the heat-cutting unit, the setting conditions for one hot air heater are such that the molten resin composition can be instantaneously heated to a temperature equal to or higher than the softening temperature of the thermoplastic resin +50°C when the distance from the tip of the hot air heater to the molten resin composition is 10 mm. Specifically, the setting conditions for the hot air force of the hot air heater are preferably 5 L / min or more, more preferably 10 L / min or more. Furthermore, the setting conditions for the hot air temperature of the hot air heater are preferably 180°C or more, more preferably 200°C or more.

[0039] The softening temperature is defined as the temperature at which a change in stress occurs due to softening of the thermoplastic resin when the change in stress is measured under a constant stress by dynamic viscoelasticity measurement. For example, when the thermoplastic resin is a P3HA-based resin, the molten resin composition of the P3HA-based resin is instantaneously heated to preferably 200°C or higher, more preferably 250°C or higher.

[0040] (Method for manufacturing press-molded thermoplastic resin products) The method for producing a press-molded thermoplastic resin product according to this embodiment includes the above-described resin supplying method as one step, and includes a press-molding step of closing the mold and press-molding a molten resin composition into the mold by the above-described resin supplying method.

[0041] In the press molding step, the mold is subjected to heat pressing using a heat press molding machine. Then, the mold after heat pressing is cooled to perform press molding. After press molding, the mold is opened to obtain a press-molded product.

[0042] The heat press molding machine used in the press molding step is not particularly limited as long as it is configured to be able to heat press the mold to which the molten resin composition has been supplied. Any conventionally known device can be used as the heat press molding machine.

[0043] (Resin supply device) A resin supplying apparatus according to one embodiment of the present invention is configured to be able to implement the resin supplying method. Figure 2 is a diagram showing a schematic configuration of a resin supplying apparatus 10 according to this embodiment. As shown in Figure 2, the resin supplying apparatus 10 includes an extruder 1, a transfer section 2, a discharge section 3, and a thermal cutting section 4.

[0044] The extruder 1 corresponds to a melting section that melts a resin composition containing a thermoplastic resin to produce a molten resin composition 11. In the extruder 1, the resin composition is fed through an inlet 1a. The resin composition fed through the inlet 1a is melt-kneaded to produce a molten resin composition 11. The melting section is not limited to the extruder 1 shown in FIG. 1 and may be any section that can melt a resin composition.

[0045] The transfer section 2 transfers the molten resin composition 11 from the extruder 1 to the discharge section 3. In the transfer section 2, the molten resin composition 11 is transferred at a constant amount to the discharge section 3. The transfer section 2 includes a constant amount discharging section that discharges a constant amount of the molten resin composition 11 toward the discharge section 3, and a transfer section main body that transfers the molten resin composition 11 discharged from the constant amount discharging section to the discharge section 3. Specifically, the transfer section 2 includes a gear pump 2a as the constant amount discharging section and a hot hose 2b as the transfer section main body. The gear pump 2a is connected to the extruder 1 and discharges a constant amount of the molten resin composition 11 toward the discharge section 3. The hot hose 2b is a hose that connects the gear pump 2a and the discharge section 3. In the transfer section 2, the molten resin composition 11 is discharged at a constant amount by the gear pump 2a and transferred to the discharge section 3 via the hot hose 2b. The constant amount discharging section is not limited to the gear pump 2a, and any known device can be used as long as it is configured to discharge a constant amount of the molten resin composition 11. Furthermore, the transfer portion main body is not limited to the hot hose 2b, and any known member can be used as long as it has a configuration capable of transferring the molten resin composition 11.

[0046] The discharge unit 3 supplies the molten resin composition 11 to the mold 5. The discharge unit 3 has a nozzle unit 31 at its tip. The molten resin composition 11 is discharged in a fixed amount from the nozzle unit 31 into the mold 5. The discharge unit 3 is not particularly limited as long as it has a configuration capable of discharging the molten resin composition 11, and any known device can be used.

[0047] The thermal cutting unit 4 heats and cuts the molten resin composition 11 discharged from the discharge unit 3 into the mold 5 instantaneously without contacting the composition. The thermal cutting unit 4 is equipped with a hot air heater 4a (hot air supply unit) that supplies hot air to the molten resin composition 11. According to the resin supplying device 10, even if the stringy portion of the molten resin composition 11 between the nozzle unit 31 and the mold 5 is cut by the thermal cutting unit 4, no new stringy portion is generated, and the molten resin composition 11 can be supplied to the mold 5 with good quantitative accuracy.

[0048] In the heat-cutting section 4, the settings of the air force and hot air temperature of the hot air heater 4a and the distance between the hot air heater 4a and the molten resin composition 11 are not particularly limited as long as the molten resin composition 11 can be heated and cut instantaneously without contact with the molten resin composition 11. For example, with regard to the distance between the hot air heater 4a and the molten resin composition 11, the distance between the tip of the hot air heater 4a and the molten resin composition 11 can be set to 10 mm.

[0049] The resin supplying device 10 may be provided with a lifting mechanism for lifting up and down the discharge part 3. Reference numerals 301 and 302 in FIG.

[0050] 3, the provision of an elevation mechanism makes it possible to change the distance between the nozzle portion 31 of the discharge unit 3 and the mold 5. For example, the distance between the nozzle portion 31 and the mold 5 can be changed depending on the adhesiveness of the thermoplastic resin used.

[0051] As shown in 301 in FIG. 3, if the stringy portion 11a of the molten resin composition 11 discharged from the nozzle portion 31 is thick, it may be impossible to instantaneously heat and cut the stringy portion 11a using the hot air heater 4a. In such a case, as shown in 302 in FIG. 3, the discharge portion 3 can be raised by the lifting mechanism to increase the distance between the nozzle portion 31 and the mold 5. This thins the stringy portion 11a to a level that allows it to be instantaneously heated by the hot air heater 4a. By providing such a lifting mechanism, it is possible to set the thickness of the stringy portion 11a of the molten resin composition 11 so that it can be instantaneously heated and cut, depending on the viscosity of the thermoplastic resin.

[0052] The lifting mechanism may be configured to change the distance between the nozzle part 31 of the discharge part 3 and the mold 5, and may be a mechanism that lifts and lowers at least one of the nozzle part 31 and the mold 5. For example, the lifting mechanism may be a mechanism that lifts and lowers the mold 5 out of the nozzle part 31 and the mold 5.

[0053] (Modification of the heated cutting section) A modified example of the thermal cutting unit 4 shown in Fig. 2 will be described. Fig. 4 is a diagram showing the configuration of a modified example of the thermal cutting unit 4 provided in the resin supplying device 10 shown in Fig. 2. As shown in Fig. 4, the thermal cutting unit 4A differs from the thermal cutting unit 4 shown in Fig. 1 in that it is provided with a hot wire 4b. That is, the thermal cutting unit 4A is provided with a hot wire 4b that does not come into contact with the molten resin composition 11 and heats it instantaneously.

[0054] The hot wire 4b is a heat source, and is, for example, a metal wire heated by electrical heating. Even with the configuration of the thermal cutting unit 4A, the stringy portion of the molten resin composition 11 can be instantaneously heated and cut by radiant heat from the hot wire 4b. In the thermal cutting unit 4A, the temperature of the hot wire 4b and the distance between the hot wire 4b and the molten resin composition 11 are not particularly limited as long as the molten resin composition 11 can be instantaneously heated and cut without contact.

[0055] (Regarding the nozzle part of the discharge section) 2, the nozzle portion 31 of the discharge unit 3 is not particularly limited as long as it is configured to be able to discharge the molten resin composition 11. Preferably, the nozzle portion 31 is configured to intermittently discharge the molten resin composition 11.

[0056] 501 in Fig. 5 is a cross-sectional view schematically showing an example of the configuration of the nozzle portion 31. As shown in Fig. 501, the nozzle portion 31 includes a nozzle body 31a, a cavity 31b, and a plunger 31c. In the nozzle portion 31, the molten resin composition is contained in the nozzle body 31a.

[0057] The cavity 31b is a hollow portion provided at the tip of the nozzle body 31a on the mold side. The cavity 31b extends vertically downward from the tip of the nozzle body 31a. The cavity 31b also communicates with the nozzle body 31a. During the discharge operation, the molten resin composition in the nozzle body 31a is discharged into the mold through the cavity 31b.

[0058] The plunger 31c has a rod-like shape that extends vertically and functions as an opening / closing mechanism for the nozzle portion 31. The opening / closing mechanism includes the plunger 31c and a moving part that moves the plunger 31c up and down. The plunger 31c moves up and down within the nozzle body 31a to open or close the communication port between the nozzle body 31a and the cavity 31b. The plunger 31c alternately opens and closes the communication port, causing the nozzle portion 31 to intermittently discharge the molten resin composition.

[0059] 502 in Fig. 5 is a cross-sectional view showing a schematic configuration of a zero-cavity nozzle 31A as a modified example of the nozzle portion 31. As shown in 502 in Fig. 5, the zero-cavity nozzle 31A differs from the nozzle portion 31 in that the cavity 31b is not provided.

[0060] In the nozzle portion 31, even when the connecting port between the nozzle body 31a and the cavity 31b is closed by the plunger 31c, the molten resin composition may remain in the cavity 31b. The residue of the molten resin composition in the cavity 31b may become the starting point for the stringing of the molten resin composition between the nozzle portion 31 and the mold. The zero-cavity nozzle 31A does not have a cavity 31b where the molten resin composition may remain, so the stringing of the molten resin composition can be prevented. Thus, the zero-cavity nozzle 31A is effective in preventing the stringing of the molten resin composition.

[0061] (thermoplastic resin) The resin composition used in this resin supply method includes a thermoplastic resin. The thermoplastic resin is not particularly limited. Preferred thermoplastic resins include general-purpose resins such as polypropylene, polyethylene, polyvinyl chloride, polyvinyl acetate, polyacetal, polycarbonate, polyamide, acrylonitrile, butadiene, polystyrene, and acrylic polymers, as well as biodegradable resins such as P3HA resin, polylactic acid, polyglycolic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polybutylene succinate terephthalate, and polycaprolactone. Molten resin compositions of these resins may exhibit the stringiness phenomenon when cut with a cutter, depending on the melting conditions of the resin composition. Furthermore, the resin composition used in this production method preferably includes a thermoplastic resin that can be used in press molding.

[0062] In particular, the thermoplastic resin used in this resin supply method is preferably a P3HA-based resin. In this specification, "P3HA-based resin" means a biodegradable aliphatic polyester (preferably a polyester containing no aromatic ring). P3HA-based resins are 3-hydroxyalkanoic acid repeating units represented by the general formula: [-CHR-CH2-CO-O-] (wherein R is C n H 2n+1 and n is an integer of 1 or more and 15 or less.) as a repeating unit.

[0063] The P3HA resin contains at least one copolymer of 3HB units and other hydroxyalkanoate units, and the 3-hydroxybutyrate units in the poly(3-hydroxyalkanoate) resin account for 94.5 to 98.5 mol %, preferably 95.0 to 98.5 mol %, more preferably 96.0 to 98.5 mol %, and even more preferably 96.5 to 98.0 mol %, of all repeating units (100 mol %).

[0064] When the composition ratio of 3HB repeating units is 94.5 mol% or more, the rigidity of the P3HA-based resin is improved, the crystallization rate is accelerated, flash is reduced, and productivity tends to be improved. On the other hand, when the composition ratio of 3HB repeating units is 98.5 mol% or less, the melting point is below the thermal decomposition temperature, enabling stable and continuous production. The monomer composition ratio of the P3HA-based resin can be measured by gas chromatography or the like (see, for example, WO 2014 / 020838).

[0065] More specifically, P3HA-based resins include copolymers of 3HB with other hydroxyalkanoates, such as poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P3HB3HV3HH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate).

[0066] P3HA resins produced by microorganisms (microorganism-produced P3HA resins) are usually P3HA resins composed only of D-form (R-form) polyhydroxyalkanoic acid monomer units. Among microbially produced P3HA resins, P3HB, P3HB3HH, P3HB3HV, P3HB3HV3HH, and P3HB4HB are preferred, with P3HB, P3HB3HH, P3HB3HV, and P3HB4HB being more preferred, due to ease of industrial production.

[0067] Microorganisms that produce microbially produced P3HA resins are not particularly limited as long as they are capable of producing P3HA resins. For example, the first P3HB-producing bacterium was Bacillus megaterium, discovered in 1925. Other examples include naturally occurring microorganisms such as Cupriavidus necator (formerly classified as Alcaligenes eutrophus and Ralstonia eutropha) and Alcaligenes latus. These microorganisms are known to accumulate P3HB within their cells.

[0068] Known bacteria that produce copolymers of hydroxybutyrate and other hydroxyalkanoates include Aeromonas caviae, which produces P3HB3HV and P3HB3HH, and Alcaligenes eutrophus, which produces P3HB4HB. In particular, for P3HB3HH, Alcaligenes eutrophus AC32 (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, pp. 4821-4830 (1997)), which has been introduced with genes encoding P3HA resin synthases, is preferred for increasing P3HB3HH productivity. These microorganisms are cultured under appropriate conditions to accumulate P3HB3HH within the cells. In addition to the above, genetically modified microorganisms into which various P3HA resin synthesis-related genes have been introduced may be used depending on the P3HA resin to be produced, and culture conditions, including the type of substrate, may be optimized.

[0069] The molecular weight of the P3HA resin is not particularly limited as long as it exhibits substantially sufficient physical properties for the intended application. The weight-average molecular weight of the P3HA resin is preferably in the range of 100,000 to 1,000,000, more preferably 150,000 to 700,000, even more preferably 200,000 to 500,000, and particularly preferably 250,000 to 450,000. A weight-average molecular weight of 100,000 or more ensures adequate mechanical strength. Furthermore, a molecular weight of 1,000,000 or less can suppress an increase in melt viscosity, resulting in excellent moldability.

[0070] The weight-average molecular weight can be measured using gel permeation chromatography (GPC) (Shodex GPC-101 manufactured by Showa Denko K.K.) with a polystyrene gel column (Shodex K-804 manufactured by Showa Denko K.K.) and chloroform as the mobile phase, and can be calculated as a polystyrene-equivalent molecular weight. A calibration curve is prepared using polystyrenes with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. A column suitable for measuring the molecular weight can be used for the GPC.

[0071] The resin composition used in this production method may contain a second P3HA resin in addition to the P3HA resin. The second P3HA resin contains at least one copolymer of 3HB units and other hydroxyalkanoate units, and the poly(3-hydroxyalkanoate) resin preferably contains 65.0 to 90.0 moles of 3HB units, more preferably 68.0 to 88.0 moles, and even more preferably 70.0 to 85.0 moles. When the resin composition further contains the second P3HA resin, the toughness of the molded article is excellent.

[0072] The second P3HA-based resin is not particularly limited as long as it is different from the P3HA-based resin described above. Examples of the second P3HA-based resin include the resins exemplified above as the P3HA-based resin.

[0073] The content of the second P3HA resin is not particularly limited, but is preferably 50 parts by weight or less, more preferably 45 parts by weight or less, and even more preferably 40 parts by weight or less, relative to 100 parts by weight of the total P3HA resin. The lower limit of the content of the second P3HA resin is not particularly limited, and may be 0 parts by weight. The P3HA resins described above can be used as the second P3HA resin. In this specification, "total P3HA resins" refers to all P3HA resins contained in the resin composition produced by this production method.

[0074] The resin composition may contain other resins besides the P3HA resin, provided that the effects of the present invention are not impaired. Examples of such other resins include aliphatic polyester resins such as polybutylene succinate adipate, polybutylene succinate, polycaprolactone, and polylactic acid, and aliphatic aromatic polyester resins such as polybutylene adipate terephthalate, polybutylene sebatate terephthalate, and polybutylene azelate terephthalate. The other resins may be contained alone or in combination.

[0075] The content of the other resin is not particularly limited, but is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and even more preferably 30 parts by weight or less, relative to 100 parts by weight of the total P3HA resin. The lower limit of the content of the other resin is not particularly limited, and may be 0 part by weight.

[0076] The resin composition does not necessarily contain an inorganic filler, but preferably further contains an inorganic filler. When the resin composition contains an inorganic filler, the crystallization rate is improved, and effects such as reducing burrs and improving the production cycle are achieved.

[0077] The inorganic filler is not particularly limited, but examples thereof include talc, diatomaceous earth, white clay, clay, calcium carbonate, manganese carbonate, magnesium carbonate, barium sulfate, mica, silica, alumina, zircon, iron oxide, zinc oxide, titanium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, graphite, carbon black, ferrite, graphite, quartz, glass fiber, glass particles, etc. These may be used alone or in combination of two or more.

[0078] The content of the inorganic filler is, for example, 0 to 60 parts by weight, preferably 5 to 50 parts by weight, more preferably 10 to 40 parts by weight, and particularly preferably 15 to 35 parts by weight, relative to 100 parts by weight of the total P3HA-based resin. When the content of the inorganic filler is within the above range, both a sufficient crystallization rate and toughness can be achieved.

[0079] The resin composition may also contain additives that can be used with the P3HA resin, provided that the effects of the present invention are not impaired. Examples of such additives include colorants such as pigments and dyes, odor absorbers such as activated carbon and zeolite, fragrances such as vanillin and dextrin, plasticizers, antioxidants, weather resistance improvers, UV absorbers, crystal nucleating agents, lubricants, release agents, water repellents, antibacterial agents, and sliding properties improvers. Only one type of additive may be contained, or two or more types may be contained. The content of these additives can be appropriately determined by those skilled in the art depending on the intended use.

[0080] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0081] That is, one embodiment of the present invention is as follows. <1> A resin supplying method comprising: a melting step of melting a resin composition containing a thermoplastic resin to produce a molten resin composition; a transfer step of transferring the molten resin composition to a discharge section; a discharge step of supplying the molten resin composition from the discharge section to a mold; and a heating and cutting step of contactlessly and instantaneously heating and cutting the molten resin composition discharged from the discharge section to the mold. <2> The heat-cutting step includes a step of heating and cutting the molten resin composition in a non-contact and instantaneous manner using hot air or a hot wire. <1> The resin supply method according to claim 1. <3> The discharging step includes a step of intermittently discharging the molten resin composition. <1> or <2> The resin supply method according to claim 1. <4> the transferring step includes a step of transferring the molten resin composition to a discharge portion using a gear pump, <1> ~ <3> The resin supply method according to any one of the above. <5> the discharging step includes a step of supplying the molten resin composition from a zero-cavity nozzle to the mold; <1> ~ <4> The resin supply method according to any one of the above. <6> The thermoplastic resin is a poly(3-hydroxyalkanoate)-based resin. <1> ~ <5> The resin supply method according to any one of the above. <7> The poly(3-hydroxyalkanoate) resin is one or more selected from the group consisting of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate). <6> The resin supply method according to claim 1. <8> <1> ~ <7> 10. A method for producing a press-molded thermoplastic resin product, comprising the resin supply method according to any one of claims 1 to 9 as one step. <9> A resin supplying device comprising: a melting section that melts a resin composition containing a thermoplastic resin to produce a molten resin composition; a discharge section that supplies the molten resin composition to a mold; a transfer section that transfers the molten resin composition from the melting section to the discharge section; and a heating and cutting section that heats and cuts the molten resin composition discharged from the discharge section to the mold in a non-contact and instantaneous manner. <10> the heat-cutting unit includes a hot air supply unit that supplies hot air to the molten resin composition, or a hot wire that heats the molten resin composition instantaneously without contacting the molten resin composition; <9> The resin supply device according to claim 1. <11> The discharge unit includes a nozzle unit that intermittently discharges the molten resin composition. <9> or <10> The resin supply device according to claim 1. <12> The nozzle portion is a zero cavity nozzle. <11> The resin supply device according to claim 1. <13> The transfer unit includes a gear pump. <9> ~ <12> The resin supplying device according to any one of the above. [Industrial Applicability]

[0082] The present invention can be suitably used in, for example, the field of producing press-molded articles using P3HA-based resins, and other fields. [Explanation of symbols]

[0083] 1. Extruder (melting section) 2 Transfer section 2a gear pump 3 Discharge part 31 Nozzle section 31A Zero Cavity Nozzle 4, 4A heating cutting section 4a Hot air heater (hot air supply part) 4b Hotwire 5. Mold 10 Resin supply device 11 Molten resin composition 101 Melting process 102 Transfer process 103 Discharge process 104 Heat cutting process

Claims

1. a melting step of melting a resin composition containing a thermoplastic resin to produce a molten resin composition; a transfer step of transferring the molten resin composition to a discharge section; a discharge step of supplying the molten resin composition from the discharge portion to a mold; a heating and cutting step of heating and cutting the molten resin composition discharged from the discharge portion into the mold in a non-contact and instantaneous manner, The resin supplying method, wherein the discharging step includes a step of intermittently discharging the molten resin composition.

2. The resin supplying method according to claim 1 , wherein the heat-cutting step includes a step of heating and cutting the molten resin composition instantaneously in a non-contact manner using hot air or a hot wire.

3. The resin supplying method according to claim 1 or 2, wherein the transferring step includes a step of transferring the molten resin composition to a discharge portion using a gear pump.

4. The resin supplying method according to any one of claims 1 to 3, wherein the discharging step includes a step of supplying the molten resin composition from a zero-cavity nozzle to the mold.

5. 5. The resin supplying method according to claim 1, wherein the thermoplastic resin is a poly(3-hydroxyalkanoate)-based resin.

6. 6. The resin supply method according to claim 5, wherein the poly(3-hydroxyalkanoate)-based resin is one or more selected from the group consisting of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate).

7. A method for producing a press-molded thermoplastic resin product, comprising the resin supply method according to any one of claims 1 to 6 as one step.

8. a melting section for melting a resin composition containing a thermoplastic resin to produce a molten resin composition; a discharge portion for supplying the molten resin composition to a mold; a transfer section that transfers the molten resin composition from the melting section to the discharge section; a heating and cutting unit that heats and cuts the molten resin composition discharged from the discharge unit into the mold in a non-contact manner and instantaneously, The discharge unit includes a nozzle that intermittently discharges the molten resin composition.

9. The resin supplying device according to claim 8 , wherein the heat cutting unit comprises a hot air supplying unit that supplies hot air to the molten resin composition, or a hot wire that heats the molten resin composition instantaneously without contacting the molten resin composition.

10. The resin supplying device according to claim 8 , wherein the nozzle portion is a zero-cavity nozzle.

11. The resin supplying device according to any one of claims 8 to 10, wherein the transfer unit includes a gear pump.

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